PHILADELPHIA (CBS) – A brawl in the hallways at Abraham Lincoln High School in the Northeast Philadelphia this Tuesday afternoon resulted in the school population being placed in lockdown.

Philadelphia School District Spokesperson Fernando Gallard says the incident happened at about 1:15.

“We don’t know what specifically triggered the fights. We do know there were three fights during a period change. Seven students ended up being arrested due to those fights. We are now working to investigate what specifically occurred between the students.”

Gallard says the school was in lockdown for less then an hour and were dismissed as normal, but the investigation is well underway.

“We conduct interviews, we work with Philadelphia police and then we will bring students back in and take the appropriate action to make sure that students are aware that we will not tolerate this type of behavior.”